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I need to create a worldfile from Bigmap Application. I've successfully to grab a pack of PNG tiles and the pearl app mosaicking all in one. The BigMap site shows the raster bounding box and util metadata:

Map is 12x12 tiles (3072x3072 px) at zoom 18, aspect 1:1 -43.475647,-22.886297,-43.459167,-22.871114 (l,b,r,t)

This is my local png map | http://goo.gl/oY8vA

This is my pgw configuration:

3072----------X?
0
0
-3072---------Y?
-43.475647----left?
-22.871114----top?

How I create a PGW file in Quantum GIS or another app?

Jorge Santos

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1 Answer 1

A world file (pgw) consists of

width of pixel
rotation about Y axis (nearly always 0)
rotation about X axis (nearly always 0)
negative height of pixel (to make the maths easier)
left edge (in the real world)
top edge (in the real world)

so in your case it should be something like:

5.364583333333333e-6
0
0
-5.364583333333333e-6
-43.475647
-22.871114 

See http://en.wikipedia.org/wiki/World_file for a full description of the different elements in a world file.

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Thanks iant, but how to calculate the worldfile XY pixel width? My raster shift to down position. Please check this print | goo.gl/Tm2Mn | What I done wrong? Jorge Santos –  Jorge Santos May 25 '12 at 11:40
1  
Line 6 is Y-coordinate of upper left corner (center of pixel) –  Stefan May 25 '12 at 12:49
    
Stefan - well spotted, I knew I should have finished my coffee before answering –  iant May 25 '12 at 12:53
    
Thanks Iant/Stefan. It Works well. –  Jorge Santos May 28 '12 at 17:44

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